To characterize non-toxic, effective anti-biofilm agents that do not affect bacterial growth, a research program is proposed to investigate the ability of naturally-occurring marine furanones and other plant-derived compounds to inhibit the formation of E. coli biofilms. In addition, the genetic basis of biofilm formation will be investigated using temporal DNA microarray studies, knock-outs, and NMR structure determinations of the discovered biofilm regulatory proteins. This project will discover the genes required for E. coli biofilm formation by two complementary approaches using DNA microarrays: direct identification of biofilm genes and by inhibiting biofilms with plant compounds. In addition, this project will identify how the plant-derived biofilm inhibitors influence biofilms, and will discover other plant-derived compounds which inhibit biofilms. The biofilm genes that are found will be rich targets for other classes of compounds that may be used to prevent biofilms in industry and medicine. The specific objectives of this project are: 1. synthesize natural furanones from the red alga Delisea pulchra and evaluate these furanones and other plant-derived compounds for their ability to prevent biofilm formation using confocal microscopy and 96-well rapid assays 2. evaluate the impact of the plant-derived inhibitors on the gene expression of E. coli using DNA microarrays (identify which genes are affected while the inhibitor does not affect growth) 3. discover biofilm genes using DNA microarrays for E. coli (submerged biofilm) 4. discover cell-to-cell signaling genes using DNA microarrays by inhibiting communication with furanones 5. study the importance of the genes elucidated with the gene chips in terms of biofilm formation and architecture using knock-out mutants that are labeled with the green fluorescence protein and by tagging the promoters of biofilm regulatory proteins 6. determine the structure and thereby the function of the important biofilm regulatory proteins using NMR 7. deduce a model for bacterial biofilm formation based on the genetic information (which genes induced/repressed) and protein information discerned (via NMR)